German Finance Minister Wolfgang Schaeuble says he could not disregard the possibility of other countries quitting the European Union if Britain decides to leave the 28-member bloc.
"You can't rule it out," Schaeuble was quoted as saying by the German news magazine Der Spiegel in an advance excerpt of an interview due to be published on Saturday.
"How would the Netherlands, which has traditionally been very closely allied with Britain, react, for example?"
Polls suggest a neck-to-neck race between the "Leave" and "Remain" camps ahead of the vote.
Schaeuble said that if Britain were to become the only country to leave the EU, he would not be concerned about the bloc's continued existence: "If need be, Europe would work without Britain."
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He said calling for more integration in the EU - as some European politicians have done - was no answer to a Brexit.
He said that even if a slim majority of Britons voted to quit the EU, "we need to understand that as a warning and wake-up call to not continue doing as we have done up until now".
Schaeuble warned Britain it could suffer economic consequences if it quits the EU given that it is closely interlinked with partner countries, the magazine said.
"It would be a miracle if Britain quitting does not have any economic disadvantages," Schaeuble was quoted as saying.
He said a Brexit could also have a negative effect on partner countries but he and his counterparts in the euro zone would do all they could to limit these consequences: "We're preparing for all possible scenarios to limit the dangers."
Schaeuble ruled out Britain being able to continue to benefit from the European single market like Norway or Switzerland if it quit: "For that the country would need to stick to the rules of the club that it now wants to quit."
